OSTREA. 



359 



Fio. 142. — Ostrea ninahuJa, Seel. Cambridge Greensand (base of Chalk Marl). A, b, British Museum, 

 Xo. ()77K1. c-i. Sed|j:wick Museum. A, B, left valve, c, left ; d. right valve ; B, antt^rior view of c, D. 

 F. rii;ht valve with other oysters on the surface, a, left valve. H, i, exterior and interior of a left valve. 

 All x §. 



